[PATCH] D37561: [ELF] - Don't crash when --emit-relocs is used with --gc-sections

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 115205.
grimar added a comment.

- Addressed review comment.

Note: https://reviews.llvm.org/D37735 should be landed first for allowing this to work properly. Because at next line:
https://github.com/llvm-mirror/lld/blob/master/ELF/OutputSections.cpp#L230
code would try to access to null pointer `Out`, when it should just report discarded end return at method start.


https://reviews.llvm.org/D37561

Files:
  ELF/InputSection.cpp
  test/ELF/emit-relocs-gc.s


Index: test/ELF/emit-relocs-gc.s
===================================================================
--- test/ELF/emit-relocs-gc.s
+++ test/ELF/emit-relocs-gc.s
@@ -0,0 +1,18 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+
+## Show that we emit .rela.bar when GC is disabled.
+# RUN: ld.lld --emit-relocs %t.o -o %t
+# RUN: llvm-objdump %t -section-headers | FileCheck %s --check-prefix=NOGC
+# NOGC: .rela.bar
+
+## GC collects .bar section and we exclude .rela.bar from output.
+# RUN: ld.lld --gc-sections --emit-relocs --print-gc-sections %t.o -o %t \
+# RUN:   | FileCheck --check-prefix=MSG %s
+# MSG: removing unused section from '.bar' in file
+# MSG: removing unused section from '.rela.bar' in file
+# RUN: llvm-objdump %t -section-headers | FileCheck %s --check-prefix=GC
+# GC-NOT:  rela.bar
+
+.section .bar,"a"
+.quad .bar
Index: ELF/InputSection.cpp
===================================================================
--- ELF/InputSection.cpp
+++ ELF/InputSection.cpp
@@ -83,7 +83,10 @@
     : SectionBase(SectionKind, Name, Flags, Entsize, Alignment, Type, Info,
                   Link),
       File(File), Data(Data), Repl(this) {
-  Live = !Config->GcSections || !(Flags & SHF_ALLOC);
+  Live = !Config->GcSections;
+  if (!(Flags & SHF_ALLOC))
+    Live = Type != SHT_REL && Type != SHT_RELA;
+
   Assigned = false;
   NumRelocations = 0;
   AreRelocsRela = false;


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